SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cfb1dd9286e111ad47213b984717db596c269eedc534dddc029af585894c905f' 
  AND token = 'LLntQFILcQTbWmwe6xTGF0pMC/SM/jAYiRvZHlrplJY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}